The use of expandable stents and other prostheses is well known in the art. Typically, stents are placed in a vessel during or after an angioplasty procedure or other procedure to maintain the patency of a bodily vessel. While stents are often used in the circulatory system, they find use in other parts of the body as well including the urinary system.
Stents are generally mechanically expandable, self-expanding or hybridxe2x80x94that is both mechanically expandable and self-expanding. A hybrid stent will generally self-expand to a certain diameter after which it is mechanically expanded to a larger diameter or opening. Mechanically expandable stents are usually expanded by the application of a radially outward force to the stent via an expansion device such as a balloon located within the stent.
In use, a stent is disposed about an expansion device such as a balloon at the distal end of a catheter. A portion of the catheter is inserted in a desired bodily vessel and advanced to a desired bodily location. The balloon or other expansion device is then expanded, thereby expanding the stent and implanting the stent at the desired bodily location. Subsequently, the balloon or other expansion device is contracted and withdrawn from the body, leaving the stent behind in the body.
Unfortunately, unless the stent is secured to the balloon or other expansion device, undesirable slipping or motion of the stent relative to the balloon or other expansion device may occur during delivery of the stent to the desired bodily location and during expansion of the stent. In order to prevent this, a number of approaches have been taken.
One approach involves crimping the stent tightly to the balloon. Care must be taken, however, to avoid puncturing the balloon and to avoid damaging the stent.
Another approach focuses on the choice of balloon materials to provide a more resilient balloon surface with less slippage of the stent relative to the balloon. More resilient balloon materials, however, may compromise non-compliance features of the balloon as well as the burst pressure of the balloon. Although the coextrusion of a base layer comprising a high strength material with a resilient top layer material has been considered, it is difficult to find compatible materials.
Yet another approach to preventing relative movement of the balloon and stent involves setting a balloon to the shape of a stent as been disclosed in U.S. Pat. No. 5,836,965 to Jendersee. The use of protrusions on a balloon to engage a stent has been disclosed in copending and commonly assigned U.S. application Ser. No. 09/283375. A stent may also be retained on a balloon via the use of sleeves or socks, as disclosed in copending and commonly assigned U.S. applications Ser. Nos. 09/407836 and 09/427805. Sleeves or socks typically overlay the ends of the stent.
Yet another approach involves the use of adhesives to glue the stent to the balloon. U.S. Pat. No. 5,100,429 discloses the use of a photodegradeable adhesive to attach a stent to an inflatable balloon. The balloon is held in place on the stent until ultraviolet energy is directed at the adhesive thereby freeing the stent from the balloon. The balloon is subsequently expanded to implant the stent.
The use of glue to secure a stent to a balloon is also disclosed in U.S. Pat. No. 5,643,278. As disclosed therein, the adhesive bond between the stent and the balloon breaks upon expansion of the balloon. Thus, once the balloon is expanded, relative motion between the stent and the balloon may occur. This may impede accurate positioning of the stent if, during expansion of the balloon, there has been any undesirable movement of the balloon away from the desired bodily location.
It is desirable to provide a stent which is adhered to a balloon prior to inflation of the balloon and following inflation of the balloon until the balloon is deflated, at which point, the stent releases from the balloon. By adhering the stent to the balloon until the balloon is deflated, the practitioner has the option, following inflation of the balloon but prior to deflation of the balloon, of adjusting the position of the stent in the body prior to release of the stent.
All U.S. patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety.
The invention in various of its embodiment is summarized below. Additional details of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below.
The present invention is directed in one embodiment to a medical device delivery apparatus comprising a catheter having an expandable and contractible member and an expandable medical device disposed about the expandable and contractible member. At least a portion of at least one of the medical device and the expandable and contractible member have a pressure sensitive adhesive applied thereto to adhere the medical device to the expandable and contractible member. The pressure sensitive adhesive is selected so as to release the medical device from the expandable and contractible member upon contraction of the member from an expanded state. Desirably, the medical device is a stent.
In another embodiment, the invention is directed to an expanded medical device disposed about an expanded expansion member on a catheter. The expanded medical device is adhered to the expanded expansion member via a pressure sensitive adhesive which releases upon contraction of the expansion member.
In yet another embodiment, the invention is directed to a method of delivering an expanded medical device to a desired bodily location comprising the steps of providing an inventive expanded medical device at a desired bodily location, contracting the expansion member thereby releasing the expanded medical device from the expansion member and withdrawing the expansion member and catheter from the body, the expanded medical device remaining at the desired bodily location.
In another embodiment, the invention is directed to a method of securing an expandable medical device for implantation in a body to an expansion member. The method comprises the steps of providing an expansion member having an inner surface and an outer surface, providing an expandable medical device having an inner surface and an outer surface, at least one of the outer surface of the expansion member and the inner surface of the expandable medical device having a pressure sensitive adhesive applied thereto and disposing the expandable medical device about the expansion member and adhering the expandable medical device to the expansion member wherein the expandable medical device in an expanded state releases from the expansion member upon contraction of the expansion member.
In yet another embodiment, the invention is directed to a medical device deliver apparatus comprising a catheter having an expandable and contractible member. The expandable and contractible member is in a contracted state. An expandable medical device is disposed about the expandable and contractible member. The expandable medical device is in an unexpanded state where at least portions of at least one of the medical device and the expandable and contractible member have a pressure sensitive adhesive applied thereto to adhere the medical device to the expandable and contractible member. The pressure sensitive adhesive is selected to release the medical device from the expandable and contractible member upon expansion of the expandable and contractible member from an unexpanded state.